Mainstream support for all Microsoft Dynamics NAV 2009 versions ends January 13th, 2015. This is the last NAV version with the classic client. Of course, NAV 2009 also has RTC client, but a lot of companies use classic client. That means, Microsoft ends with classic client support.

Maybe, this is the right moment to think about upgrade to the newer NAV versions. In this situation I recommend NAV 2015. With the new Microsoft Dynamics policy, we have new cumulative updates every month, and if you use them, you will stay current in the future. That means, you will not have a need for new upgrade in following years, because you will always have the newest version. This will make a less of your investment in the future and less your users adapts to new versions – a lot of benefits.

Source: https://mbs.microsoft.com/customersource/northamerica/NAV/support/support-news/MainstreamSupportNAV2009